Hello, I'm new to this forum and a novice in electronics. My project is a relay module that switches four 6VDC circuits using the output of the parallel cable from my computer. It works OK but I am asking advice on protecting my circuit, especially the computer. I'm also concerned about how much current the parallel cable may be sinking.
The relays operate two smalll DC motors that are powered by D-cell batteries (6V). I'm using four power leads from the parallel cable (5V) and a common ground lead from the same cable.
On the PCB I have soldered four SPST reed relays and one diode. It is wired very simple: The battery (+) terminal is wired to the positive terminal of the relay. The ground terminal of the relay is wired to the motor. Another wire from the motor to the (-) battery terminal. The relay is basically a switch in this circuit.
A parallel cable +5V pin is wired to one side of the relay coil. The other side of the coil is wired back to the ground pin on the parallel cable. I have placed a diode in the current path of this circuit.
I tried a 47K ohm resistor in the coil circuit. The relay would not operate so I took it out.
Everything is working properly but I worry that too much current is being drawn through the coil and back to my PC card. The relays say "250 ohm" on them. They are rated for up to 0.5A
Is this a safe circuit for my PC?
The relays operate two smalll DC motors that are powered by D-cell batteries (6V). I'm using four power leads from the parallel cable (5V) and a common ground lead from the same cable.
On the PCB I have soldered four SPST reed relays and one diode. It is wired very simple: The battery (+) terminal is wired to the positive terminal of the relay. The ground terminal of the relay is wired to the motor. Another wire from the motor to the (-) battery terminal. The relay is basically a switch in this circuit.
A parallel cable +5V pin is wired to one side of the relay coil. The other side of the coil is wired back to the ground pin on the parallel cable. I have placed a diode in the current path of this circuit.
I tried a 47K ohm resistor in the coil circuit. The relay would not operate so I took it out.
Everything is working properly but I worry that too much current is being drawn through the coil and back to my PC card. The relays say "250 ohm" on them. They are rated for up to 0.5A
Is this a safe circuit for my PC?